Characterization and Analysis of a Biofilm-Associated Protein ORF1798 from Staphylococcus aureus

Staphylococcus aureus is an important nosocomial and community-associated pathogen that causes a variety of human diseases. The ability to adhere and subsequently form biofilms on indwelling medical devices attributes to the pathogenesis of S. aureus. As is generally known, bacteria embedded in the biofilm are extremely resistant to antibiotics and the host immune defense system, which makes medical treatment difficult and imposes high financial losses. Biofilm is a tenacious structure formed by bacteria on solid surfaces. Once the structure is developed, it is difficult to eradicate. To have a better understand on the mechanisms of biofilm formation is critical to prevent and control biofilm-associated infections. The ability for biofilm formation is dependent on the genetic constitution; the genes for both bacterial adherence and accumulation must be present for biofilm formation. To identify the genes that are involved in biofilm formation by S. aureus, we constructed a mutant library, which contains approximately 2000 transposon insertional mutants. From a screening work, a mutant, S. aureus M1798, which is defective in forming biofilm on polystyrene surface, was selected for further study. S. aureus M1798 with a mutation in orf1798, which encoded a hypothetical membrane protein, forms 82% less biofilm than does the parental strain, S. aureus RN1HG. The mutation in orf1798 affects bacterial primary attachment, cellular accumulation, and production of polysaccharide intercellular adhesin (PIA), a substance that is required for biofilm formation, indicating that orf1798 is critical to biofilm formation. Meanwhile, S. aureus M1798 was complemented with pHY1798, which carries the wild type orf1798 genes, restores the capacity of the organism to form biofilms. The objective of this study is to investigate how orf1798 affects biofilm formation. Biofilm-associated phenotypes of the mutant will be examined. This study will also analyze the expression and functions of orf1798 and ORF1798. The orf1798-associated mechanisms for biofilm formation will also be elucidated. The information obtained from this work will reveal the mechanisms that are important to biofilm formation and pathogenesis of S. aureus and be valuable for the development of effective strategies to prevent and control this microorganism in diverse disease settings.

Project ID:PC10301-0304
External Project ID:NSC102-2320-B182-027-MY3